The present invention relates, in general, to radiant energy and, in particular, to analyte supports.
Optical techniques cannot be used to observe extremely fine features such as those on the surface of a semiconductor integrated circuit, because the wavelength of visible light is too large to distinguish such fine features. Therefore, particles in the form of an electron beam, or e-beam, is used because an e-beam can be generated that with a sufficiently small wavelength to distinguish such features.
Three types of e-beam microscopes have been developed: Transmission Electron Microscope (TEM), Scanning Transmission Electron Microscope (STEM), and Scanning Electron Microscope (SEM). Each of these microscopes operated by accelerating an e-beam of toward the surface of an object to be viewed. When the e-beam strikes the surface of the object, secondary electrons are emitted from the object. To prevent an electric charge from accumulating on the surface, the object is often coated with a metal prior to being bombarded with an e-beam. The secondary electrons are then collected by a detector called a secondary emission detector (SED). The detected secondary emission is then coordinated with the excitation signals applied to the e-beam to extract an image of the object.
The TEM, which is very expensive, generates an unmovable e-beam spot onto an object of interest to produce an image of very high resolution. The STEM, which is also very expensive, generates an e-beam that is scanned over an object of interest to produce an image of very high resolution. The SEM, which is approximately ten times less expensive than either a TEM or a STEM, generates an e-beam that is scanned over the object of interest to produce an image of high resolution, but not as high as that of either a TEM or a STEM.
In a book entitled xe2x80x9cScanning Electron Microscopy and X-ray Microanalysis, a Text for Biologists, Materials Scientists, and Geologists, 2Ed.,xe2x80x9d by Joseph I. Goldstein et al., published in 1992, pps. 267-270, it was disclosed that the resolution of a STEM may be achieved in a SEM by mounting a thin sample of the item to be viewed across an opening in a sample stage, placing either a scintillator coupled to a light pipe or a solid-state detector below the sample stage. The disadvantages of this method are that lateral scattering of electrons passing through the sample will determine the upper limit of image resolution and placing a scintillator and light-pipe or solid-state device under the sample stage requires modifications to the SEM which result in time-consuming setup procedures. Goldstein et al. also suggests using a tilted scattering surface of a high-atomic number. The disadvantage of this method is that lateral scattering of electrons passing through the sample will determine the upper limit of image resolution.
U.S. Pat. No. 4,596,929, entitled xe2x80x9cTHREE-STAGE SECONDARY EMISSION ELECTRON DETECTION IN ELECTRON MICROSCOPES,xe2x80x9d discloses a device that uses two grids to maximize the amount of secondary emission detected by a scintillator. The present invention does not employ two such grids. U.S. Pat. No. 4,596,929 is hereby incorporated by reference into the specification of the present invention.
U.S. Pat. No. 4,627,009, entitled xe2x80x9cMICROSCOPE STAGE ASSEMBLY AND CONTROL SYSTEM,xe2x80x9d discloses a device for rotating and tilting a sample in a non-eucentric manner and compensate for the same so that an inspection point is within the field of view. The present invention does not rotate and tilt a sample in a non-eucentric manner and compensate for the same so that an inspection point is within the field of view. U.S. Pat. No. 4,627,009 is hereby incorporated by reference into the specification of the present invention.
U.S. Pat. No. 5,179,280, entitled xe2x80x9cCOMPUTER CONTROL OF THE ELECTRON MICROSCOPE SAMPLE STAGE,xe2x80x9d discloses a device for tilting a sample so that a plurality of different orientations are displayed stereoscopically with a spot representing a current orientation. The present invention does not tilt a sample so that a plurality of different orientations are displayed stereoscopically with a spot representing a current orientation. U.S. Pat. No. 5,179,280 is hereby incorporated by reference into the specification of the present invention.
U.S. Pat. No. 5,510,624, entitled xe2x80x9cSIMULTANEOUS SPECIMEN AND STAGE CLEANING DEVICE FOR ANALYTICAL ELECTRON MICROSCOPE,xe2x80x9d discloses a device for cleaning both a sample stage, a sample, and an interior of an analytical electron microscope. The present invention does not clean either a sample stage, a sample, or an interior of an analytical electron microscope. U.S. Pat. No. 5,510,624 is hereby incorporated by reference into the specification of the present invention.
U.S. Pat. No. 6,025,592, entitled xe2x80x9cHIGH TEMPERATURE SPECIMEN STAGE AND DETECTOR FOR AN ENVIRONMENTAL SCANNING ELECTRON MICROSCOPE,xe2x80x9d discloses a device that can heat a sample to 1500 degrees Celsius. The present invention does not heat a sample to 1500 degrees Celsius. U.S. Pat. No. 6,025,592 is hereby incorporated by reference into the specification of the present invention.
U.S. Pat. No. 6,407,850, entitled xe2x80x9cAUTO TILT STAGE,xe2x80x9d discloses a device for tilting a sample stage to multiple positions. The present invention does not tilt a sample stage to multiple positions. U.S. Pat. No. 6,407,850 is hereby incorporated by reference into the specification of the present invention.
It is an object of the present invention to obtain the image resolution of a scanning transmission electron microscope in a less expensive scanning electron microscope.
It is another object of the present invention to obtain the image resolution of a scanning transmission electron microscope in a less expensive scanning electron microscope by using a graphite collimator and a two-stage reflector.
The present invention is a sample-stage for obtaining the image resolution of a scanning transmission electron microscope in a less expensive scanning electron microscope.
The sample stage includes a base, a horizontal support member, a vertical support member, a collimator, a first reflector, and a second reflector.
The base has a left end, a right end, and a top surface.
The horizontal support member has a left end, a right end, a top surface, a bottom surface, and a first aperture perpendicular to the top surface and between the left end and the right end.
The vertical support member has a bottom surface, a top surface, a left side, and a right surface. The bottom surface of the vertical support member abuts the left side and top surface of the base. The top surface of the vertical support member abuts the left end and bottom surface of the horizontal support member so that a portion of the right surface of the vertical support member is directly below the first aperture of the horizontal support member. The right surface of the vertical support member nearest the top surface of the vertical support member is to the left of the first aperture of the horizontal support member. The right surface of the vertical support member nearest the bottom surface of the vertical support member is to the right of the first aperture of the horizontal support member to form a user-definable.
The first reflector, which abuts the right surface of the vertical support member, is a layer of a suitably high atomic number material.
The second reflector, which abuts the portion of the top surface of the base that is not covered by the vertical support member, is a layer of a suitably high atomic number material.
The collimator has a top surface, a bottom surface, a left side, a right side, and a second aperture perpendicular to the top surface and completely through the. The bottom surface of the collimator abuts the top surface of the horizontal support member so that the first aperture of the horizontal support member and the second aperture of the collimator are in alignment.